Word processing programs are commonly used to create and edit documents. To create a document using a word processing program, an author typically enters the text of the document using a keyboard. For a language system having a limited number of alphabet characters, each alphabet character is assigned to a different key of the keyboard. For example, the English language system uses twenty-six alphabet characters. Most keyboards have approximately 101 keys, so each English language alphabet character is assigned to a different key. To enter a word, an author depresses the keys which correspond to the letters of the words of the document and the keystrokes are sent directly from the keyboard to the word processing program.
In contrast to the English language system, some language systems have significantly more characters than there are keys on a keyboard. For example, the Japanese language system uses approximately 6,300 kanji characters. Because the number of kanji characters precludes assigning each kanji character to a different key, a phonetic input method is used to enter a Japanese document. To use the phonetic input method, an author enters a combination of keys which correspond to the syllables of the kanji character. Typically, a front-end input processor converts the keystrokes into syllabic characters and then converts the syllabic characters into kanji characters.
A phonetic input method for a Japanese keyboard may convert combinations of Latin characters into kana characters. A kana character is a syllabic character. There are two commonly used sets of kana, Hiragana and Katakana. Each set includes 46 characters. For example, if an author enters "k" and then enters "a", the kana character corresponding to the syllable "ka" is displayed on the display device. Once the kana characters are entered, the kana characters may be converted into kanji characters by depressing a conversion key.
A Japanese document may include kana and kanji characters, as well as English language words or text strings. Typically, an author uses one input mode to enter kana and then manually switches to another input mode to enter an English language text string. The author's input rhythm is disrupted when the author must stop typing and switch to a different input mode to enter the English language text string. Once the English language text string is entered, the author's input rhythm is again disrupted when the author must stop typing to return to the previous non-Latin input mode.
One solution to the mode switching problem uses a dictionary. For example, the "ATOK 11" front-end input processor used with the "ICHITARO" word processing program, uses a dictionary of learned words. If an author enters a kana string corresponding to one of the learned words, then the learned word is converted to an English language text string when the conversion key is pressed. One drawback of the ATOK 11 solution is that it only works for learned words. If a word is not in the dictionary of learned words, then the word is not converted. Another drawback is that the kana string is not converted until the conversion key is depressed, so the English language characters are not immediately displayed. The delay in displaying the English language characters makes it difficult for an author to review a document as the document is entered. Yet another drawback is that a kana string may be converted incorrectly. For example, a kana character intended by the author to remain as a kana character (or to be converted into kanji) may be erroneously converted into English language characters or a kana character at a boundary of a kana string intended by the author to be converted may not be converted.
Another solution to the mode switching problem automatically detects the depression of the shift key. For example, the "IME '97" front-end input processor marketed by Microsoft Corporation of Redmond, Wash. detects the depression of the shift key in combination with an alphabet key and automatically switches into an input mode appropriate for entering a capitalized English language character. A disadvantage of the IME '97 method is that the input mode is not automatically returned to the previous mode once a capitalized English language text string is entered. To return to the previous input mode, the user must intervene. For example, the user may manually select the previous input mode or determine the previously entered text. To determine the previously entered text, the user typically depresses a character determination key, such as the enter key, to accept the displayed text.
Many of the English language text strings included in a Japanese document are capitalized. Capitalized terms include abbreviations, such as PC (personal computer), OS (operating system) or HTML (hypertext markup language). Although the IME '97 method switches input modes when the shift key is depressed in combination with an alphabet key, the IME '97 method does not return to the previous mode when only an alphabet key is depressed. If the input mode could be automatically returned to the previous mode, then the author's input rhythm would not be disrupted to return to the previous non-Latin input mode once an English language text string is entered.
Accordingly, there is a need in the art for a method for automatically switching input modes to enter a capitalized text string and then automatically returning to the previous input mode once the capitalized text string is entered.